Heat engines are well known for their ability to convert heat energy to usable work. Heat engines such as steam engines, steam and gas turbines, diesel engines, and Stirling engines can provide power for transportation, machinery, or producing electricity, to name a few.
Rotary heat engines have a rotating hub of dynamic chambers, containing a working fluid, that are coupled to work-transfer elements to deliver mechanical work-output. They operate in a cyclical manner. Heat is added to the confined working fluid during a portion of the cycle and heat is rejected from the working fluid during another portion of the cycle. Heat causes expansion of the working fluid as work is performed. A portion of the work is used to compress the working fluid as heat is rejected. The work performed by the working fluid during expansion minus the work used to compress the working fluid during compression is the net work available to overcome friction and deliver mechanical work-output.
Because heat engines cannot convert all the input energy to useful work, some of the heat is not available for mechanical work, where the percentage of thermal energy that is converted to mechanical work defines the thermal efficiency of the heat engine. The theoretical upper limit of efficiency of a heat engine cycle is that of the Carnot Cycle. Practical heat engines such as the Rankine, Brayton, or Stirling engines operate on less efficient cycles. Typically, the highest thermal efficiency is achieved when the input (heat zone) temperature is as high as possible and the output (cold zone) temperature is as low as possible.
The Carnot cycle has long been considered the ideal heat engine cycle. It has been the goal of many heat engine designers. However, to attain Carnot cycle efficiency would be meaningless, since no power would be developed. Attempts have been made to improve the efficiency of heat engines. But, maximum power of a heat engine occurs at efficiencies considerably below Carnot cycle efficiency. Carnot cycle efficiency is only a limit of efficiency, not necessarily an ideal goal. Of course, it is desirable to balance desired power, efficiency, and cost.
There are many, many heat engine designs. There are internal combustion engines, external combustion engines, piston engines, turbine engines, rotary engines and many others. The instant invention is a closed cycle rotary heat engine.
The following patents appear to have relevancy to the instant invention:    1. U.S. Pat. No. 3,169,375, Rotary Engines or Pumps, by Velthuis, Feb. 16, 1965    2. U.S. Pat. No. 3,698,184, Low Pollution Heat Engine, by Barrett, Oct. 17, 1972    3. U.S. Pat. No. 3,867,815, Heat Engine, by Barrett, Feb. 25, 1975    4. U.S. Pat. No. 4,089,174, Method and Apparatus for Converting Radiant Solar Energy into Mechanical Energy, by Posnansky, May 16, 1978    5. U.S. Pat. No. 4,357,800, Rotary Heat Engine, by Hecker, Nov. 9, 1982    6. U.S. Pat. No. 4,502,284, Method and Engine for the Obtainment of Quasi-isothermal Transformation in Gas Compression and Expansion, by Chrisoghilos, Mar. 5, 1985    7. U.S. Pat. No. 4,621,497, Heat Engine, by McInnes, Nov. 11, 1986    8. U.S. Pat. No. 5,325,671, Rotary Heat Engine, by Boehling, Jul. 5, 1994
Except for Patent 7, they describe attempts to increase efficiency and power by circulating the working fluid external from the working chambers for heating and cooling. This, however, dilutes ideal isothermal expansion and isothermal compression, during the heating and cooling stages. Patents 6 and 8 more nearly provide ideal expansion and compression, since they minimize the heating and cooling areas being open to more than one working chamber at a time.
However, a second loss of efficiency for all of the Patents 1 through 8 occurs because heat is conducted from the hot areas to the cold areas by paths other than through the working fluid. Such a path would be through the housing.
A third loss of efficiency for all of the Patents 1 through 8, is the lack of defined dimensional parameters to assure proper temperature, pressure, and volume relationships of the working fluid.
What is needed is a heat engine that optimizes heat engine power and/or efficiency by having proper parametric relationships of temperature, pressure, and volume, as well as minimizing loss of efficiency by preventing heat loss by maximizing the amount of heat transfer from the heating areas to the cooling areas through the working fluid, and minimizing heat transfer through other conduction paths.